Ion exchange is a well known, commercially practiced process and is widely reported in the open literature. A review of ion exchange technology is given in "Kirk-Othmer Cyclopedia of Chemical Technology" (3rd ed., Vol. 13, p. 678-705, by R. M. Wheaton and L. J. Lefevre, published by Wiley and Sons). As disclosed in the aforesaid Kirk-Othmer reference, conventional ion exchange resins normally have sulfonic acid functionality, but it is known to prepare ion exchange resins having other types of functional groups. For example, ion exchange resins having functional groups which chelate metals (e.g. thiols, amines) are used in the hydro-metallurgical industry. It is also known to prepare carbamate functionalized resins by reacting an amine functionalized resin with carbon disulfide (see Chemical Abstracts, vol. 102: 46764e U.S. Pat. No. 4,670,160 and U.S. Pat. No. 4,731,187). However, as will be apparent to those skilled in the art, the carbon-nitrogen bond reduces the stability of this functional group.
Heretobefore, there has not existed an ion exchange resin having carbodithioate functionality.